Electromagnetic devices



May 26, 1959 R. B. IMMEL ELECTROMAGNETIC DEVICES Filed Feb. 29. 1956 M R m 0 m T I N E B V N h I D.

WITNESSES Unie ELECTRUMAGNETIC DEVICES Application February 29, 1956, Serial No. 568,558

3 Claims. (Cl. 317-458) My invention relates, generally, to electromagnetic devices and more particularly to electromagnets for electromagnetically-actuated relays and contactors.

In electromagnetic relays of a certain type, for example, the one described in Patent No. 2,693,553, issued November 2, 1954, to B. C. Wells and B. S. Layson, the base which supports the arc box and stationary contact structure constitutes part of the magnetic circuit for the electromagnet which actuates the movable contact member or members. The foregoing arrangement requires that the entire base be made from high grade magnetic material which is relatively expensive. Also, such material may become critical under certain world conditions. Furthermore, in the relay described in the aforesaid patent the cores for the electromagnet are first reduced in diameter at one end and then riveted into the base plate, thereby requiring separate operations which increase the manufacturing cost.

An object of my invention is to simplify the structure and reduce the manufacturing cost of electromagneticallyactuated devices, such as relays and contactors.

Another object of my invention is to provide an integral, generally U-shaped magnet core which is formed Separately from the base which supports the core and other components of an electromagnetically-actuated device.

A further object of my invention is to provide a separately formed, generally U-shaped magnet core which may be readily attached to a supporting base.

Other objects of my invention will be explained fully hereinafter or will be apparent to those skilled in the art.

In accordance with one embodiment of my invention, a generally U-shapcd magnet core is forged from round stock of magnetic material, flattened at the bight of the U and spot welded to a sheet metal base which supports the electromagnet assembly and the arc box in which the stationary contact members of a relay are mounted. The movable contact members are actuated by the armature for the electromagnet. Thus, the magnet core, which is composed of relatively expensive material, is formed separately from the base which is composed of relatively inexpensive material.

For a better understanding of the nature and objects of my invention, reference may be had to the following detailed description, taken in conjunction with the accompanying drawing, in which:

Figure 1 is a view, in side elevation, of an electromagnetically-actuated relay embodying the principal features of the invention;

Fig. 2 is a view, in perspective, of the base and magnet core provided for the relay;

Fig. 3 is another view, in perspective, of the base and magnet core, and

Fig. 4 is a view, in perspective of the magnet core.

As previously explained, the electromagnetic relay shown in Fig. 1 is fully described in the aforesaid Patent No. 2,693,553. Therefore, it will not be described States Patent 2,888,616 Patented May 26,

in detail in this application. Briefly, the relay structure comprises a base 10 and an electromagnet assembly 11, an armature assembly 12 and an arc box assembly 13. A contact arm 14, Which is actuated by the armature assembly 12, carries contact members 15 and 16 which are disposed to engage stationary contact members 17 and 18, respectively, mounted in the arc box 13.

The armature assembly 12 comprises an armature plate 21 which is attached to an armature bearing plate 22. The bearing plate 22 is movably mounted on hinge pins 23 which are mounted in a supporting plate 24 attached to pole plates 25 of the electromagnet assembly justing the spring 27 and armature 21 is fully described in the aforesaid patent. Also, the manner of adjusting the arc box to shift the stationary contact members in accordance with changes made in the position of the armature and the contact arm 14 is described in the aforesaid patent.

As explained hereinbefore, the electromagnet utilized in the relay described in the aforesaid patent comprised a base plate, composed of magnetic material, and two cores which were so located in the base plate that the plate constituted part of the magnetic circuit. Since the plate was of sufficient size to permit the arc box 13 to be mounted upon the plate, the plate was relatively large in size and required a relatively large amount of the magnetic material which is relatively expensive and may become critical under certain world conditions.

In order to reduce the amount of magnetic material required, thereby reducing the cost of the electromagnet, I have provided the base plate and core assembly shown in Figs. 2 and 3 of the drawing. As shown, the base plate 16 is composed of sheet metal and is of a channel shape having flanges 31 at opposite edges of the plate 10. The plate 10 is provided with recessed openings 32 to permit the relay structure to be mounted on a supporting panel (not shown).

As shown, an integral, generally U-shaped magnet core 33 is mounted on the bottom surface of the base plate 10 and has round legs 34 which extend through openings 35 provided in the plate It). The magnet core 33 may be forged from round stock of a special iron having the desired magnetic properties. As shown, the base or bight 36 of the U is substantially fiat, and it may be attached to the sheet metal base 10 by spot welding or other suitable means. The flattening of the bight 36 ermits the core 33 to be readily attached to the base 10. Furthermore, the flattened portion of the magnet core does ont extend beyond the flanges 31 on the base which permits the base to be readily attached to a supporting panel.

As shown, a tapped pole 37 is provided in the end of each leg 34. Thus, a pole plate 25 may be attached to each leg by means of a threaded screw 33 as shown in Fig. 1. A coil 39 is mounted on each leg 34 of the magnet core 33. The coils are retained in position by the pole plates 25 and the screws 38.

Actual tests of a relay having an electromagnet constructed in the present manner show that the operating characteristics of the present relay are substantially the same as those of the prior relay. The cost of manufacturing the forged magnet core and the formed sheet metal base plate is materially less than the cost of the prior base plate and core. The present structure res quires less iron and is lighter in weight than the prior structure.

Furthermore, it is necessary to put only the forged cores in an annealing furnace, while formerly the entire core and base plate assembly was placed in the furnace. Therefore, more cores can be stacked in the furnace for each annealing operation which makes it possible to increase the production of the cores. There fore, the present electromagnet and base plate assembly is an improvement over the prior assembly.

Since numerous changes may be made in the above described construction, and different embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all matter contained in the foregoing description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. In an electromagnet, in combination, a thin sheet metal channel-shaped base, an integral generally U-shaped magnet core attached to said base, said U-shaped core having a substantially fiat bight portion disposed between the flanges of said channel-shaped base, the legs of said core extending through said base to provide a magnetic circuit through the core independently of said base, and a coil mounted on each leg of the U-shaped core, said base being disposed between said coils and the flat bight portion of said core.

2. In an electromagnet, in combination, a thin sheet metal channel-shaped base, an integral generally U-shaped magnet core having round legs and a substantially flat bight attached to said base, said bight being disposed be tween and not extending beyond the flanges on said base,

the legs of said core extending through said base to provide a magnetic circuit through the core independently of said base, and a coil mounted on each leg of the core, said base being disposed between said coils and the bight of the U-shaped core.

3. In an electromagnet, in combination, a thin sheetmetal base having flanges on opposite edges thereof, an integral separately formed generally U-shaped magnet core having round legs and a substantially flat bight, said core being composed of a material having magnetic properties better than the magnetic properties of the base, said legs extending through openings in said base, said bight being disposed between said flanges and attached to said base, the edges of said flanges extending beyond the bottom of said base at least as far as the bottom of said bight, and a coil mounted on each leg of the U-shaped core, said base being disposed between said coils and the bight of the U-shaped core to cause magnetic flux to flow through said core independently of said base when the coils are energized electrically.

References Cited in the file of this patent UNITED STATES PATENTS 710,946 Burlingham Oct. 14, 1902 812,445 Pape Feb. 13, 1906 1,230,429 Palmer June 19, 1917 1,684,929 Snavely Sept. 18, 1928 2,693,553 Wells et a1. Nov. 2, 1954 2,796,590 Barnett June 18, 1957 2,800,620 Ebbeler et al July 23, 1957 FOREIGN PATENTS 885,836 France June 15, 1943 

